Avalanche Forecast

Issued: Apr 2nd, 2014 9:14AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Deep Persistent Slabs.

triley, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Overnight and Thursday: Freezing level dropping to valley bottoms overnight and the rising up to 1800 metres during the day. Becoming overcast with moderate to strong Southwest winds and flurries or light snow.Friday: Freezing level dipping down to about 1500 metres and the rising up to about 1700 metres. Moderate Westerly winds with periods of snow at higher elevations.Saturday: Little or no drop in freezing overnight. Continued moderate to strong Westerly winds combined with light snow above 1600 metres.

Avalanche Summary

Some storm slab avalanches that were 10-40 cm deep ran naturally or were skier triggered up to size 2.0. Snowballing and loose wet slides up to size 1.5 were also reported from solar aspects.

Snowpack Summary

Forecast new snow and Southwest wind may result in a new storm slab. High freezing levels may limit crust recovery before the new snow arrives. There are a few crusts in the snowpack that we are following. The March 25th crust is now down about 20-30 cm buried below a well settled layer of recent snow. The March 10th crust is buried down 60-90 cm and is reported to be widespread across the region up to about 2000 metres elevation. The facet/crust persistent weakness buried at the beginning of February is now down 70 - 200cm, and has been highly variable in terms of reactivity. In areas where the strong and supportive crust exists, triggering this layer has become unlikely. Avalanches releasing on this deeply buried weak layer could be very large and destructive.

Problems

Storm Slabs

Forecast new snow and Southwest wind are expected to develop new storm slabs that may not bond to the old surface in areas where the crust re-freezes before the storm. Rain at lower elevations may result in loose wet slides.

Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Deep Persistent Slabs

The new load of storm snow combined with high freezing levels may "wake-up" the deeply buried weak layer of crusts and facets. Conservative terrain selection is required during any period of change when dealing with this persistent weak layer.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Apr 3rd, 2014 2:00PM